As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE TRAINING FOR A CHECK RIDE, POWER WAS PULLED BACK TO SIMULATE ENGINE AT CONDITION. WHEN POWER WAS REAPPLIED, ENGINE FAILED TO RESPOND ENGINE WAS SECURED, TROUBLESHOOTING DECIDED PROP GOV FAILED. PROP GOV WAS REPALCED WITH OVERHAULED UNIT, ALL CHECK SAT. SUSPECT BROKEN COUNTERWEIGHT IN GOVN WAS THE PROBLEM. (K)